The state of Michigan asked the U.S. Department of Energy to analyze the potential energy effect and cost-effectiveness of the lighting requirements in ASHRAE Standard 90.1-2004 as they consider adoption of this energy code in place of ASHRAE Standard 90.1-1999. The primary change of interest in the lighting section of the 90.1-2004 Standard is the set of revised interior lighting power densities that provide for stricter lighting compliance levels.